A request made to FDA by a drug sponsor, leading to the issue of a Written Request by FDA. A Written Request (WR) is a legal document laying out the conditions under which a pediatric clinical trial should be conducted. In turn, the Written Request has the benefit for the sponsor of extending the marketing exclusivity of a drug before expiry of patent protection. The PPSR which initiates this process, identifies the studies a sponsor is planning to conduct, forms the basis for the subsequent WR and initiates the WR request process. The WR lays out the indication, types of studies to be performed, numbers of patients per study/arm, study safety and efficacy parameters and the pediatric patient age groups to be studied.